Before you head out to the garden this weekend, think twice about what you plan to spray on it.

Pesticides cause genetic damage, cancer, nervous system disorders and reproductive problems, the Ontario College of Family Physicians warned yesterday.

"People need to think long and hard before using pesticides in order to have a lawn that looks like a golf green," Dr. Cathy Vakil of Queen's University told a news conference at Queen's Park.

The college conducted a 14-month review of over 250 in-depth studies around the world on the effects of pesticides and concluded they are strongly linked to prostate, brain and pancreatic cancer as well as acute leukemia and non-Hodgkin's lymphoma.

They also may increase the rate of birth defects, fetal death and infertility, can have mental health impacts and cause disorders such as Parkinson's.

"Given the wide range of commonly used home and garden products associated with health effects, the college's overall message to patients is to avoid exposure to all pesticides whenever and wherever possible," it said in a statement.

"Our review does not support the idea that some pesticides are safer than others; it simply points to different health effects for different classes of pesticides," said Dr. Margaret Sanborn of McMaster University.

The city of Toronto has passed a bylaw prohibiting the cosmetic use of chemical herbicides and insecticides on home lawns starting this month. Homeowners violating the law will be given a warning this year but fines will go into effect in September, 2005.

Sanborn urged the Ontario government to follow the lead of Quebec and ban cosmetic pesticides on a provincial level to save every municipality from the time and cost of a lengthy review of the medical evidence.

Under the Quebec law, the most common lawn and garden pesticides such as 2,4-D and MCPA, will be banned from sale and use starting next year.

While those who work with pesticides, including farmers and golf course superintendents are most at risk, "perhaps most striking is that work exposures among parents can result in an increased risk of significant health problems including kidney cancer and brain cancer in their children," Sanborn said.

Even home and garden use of pesticides is associated with brain cancer, childhood leukemia and amyotrophic lateral sclerosis (ALS), she said.